This research develops a nonconvex model for measuring the spatial efficiency of siting decisions and demonstrates the virtues of such measurements in comparison to those of convex approaches. Working with a case study from the public sector, we develop relative spatial efficiency (RSE) models which access the sufficiency of a location decision in relation to a best practice decision on the efficient (or most accessible) frontier. The paper also compares the results of the nonconvex methodology with that of the convex model and suggests the strengths and weaknesses of each in terms of the type of support they offer to decisionmakers concerned with actual siting decisions.